In view of the widespread use of household chemical products in living environments, the hazards posed by the chronic exposure to these products are being explored (Bearth et al., 2020; Gummin et al., 2017; Kim et al., 2013; Lee and You, 2020) and they justify the strict enforcement of related regulations. However, the efficient compliance with such regulations and their establishment requires the identification of the harmful components of these products and the detailed evaluation of the related exposure hazards. Among other reasons, the fact that the toxicities of these components significantly depend on the exposure route, i.e., inhalation, ingestion, or dermal contact (Gagnon and Fromm, 2015; Galić et al., 2020; Joshi and Adhikari, 2019; Krishtal et al., 2019; Zhang et al., 2010), complicates the said evaluation. 

The harmfulness of shampoo, a representative household chemical product, has been extensively studied, as exemplified by the numerous works involving the analysis of its major components and harmful ingredients, toxicity testing, and safety assessment (Guzmán and Santini, 2019; Hidalgo et al., 2017; T Chiu et al., 2015). Surfactants, ethylene oxide, and 1,4-dioxane have been identified as the main harmful components of shampoo, with surfactants having the largest mass content (Jinot et al., 2018; Li et al., 2018; Mainkar and Jolly, 2001; Zenker et al., 2003), which mainly consist by sodium lauryl sulfate (SLS), ammonium lauryl sulfate, sodium laureth sulfate (SLES), and ammonium laureth sulfate (Jurek et al., 2019). According to the Globally Harmonized System, these four surfactants have low or no acute toxicity via inhalation, ingestion, and dermal exposure (Kim et al., 2013; Petit et al., 2017). However, in view of the chronic exposure of most humans to shampoo, repeated toxicity studies are needed for these surfactants. In the case of oral exposure, the no-observed-adverse-effect level of SLS is 100–400 mg kg−1 day−1, which, in the case of shampoo, is difficult to achieve in practice, with notable exceptions being sub-chronic oral toxicity studies in rats using repeated doses (Kumar et al., 2014). However, in the case of inhalation exposure, data pertaining to the sub-chronic and chronic toxicity of surfactants are scarce, as it is assumed that the repeated inhalation exposure of humans to shampoo does not occur. Therefore, one needs to experimentally check whether inhalation exposure to shampoo is possible and thus confirm or disprove the necessity of acquiring repeated inhalation toxicity data for surfactants. 

Herein, the possibility of inhalation exposure to shampoo was evaluated by simulating the actual use of shampoo, and the potential of exposure to the generated shampoo aerosol was evaluated by analyzing the aerosol particle size and composition. The obtained results demonstrate the need to inform consumers of the necessity of evaluating the risks posed by shampoo inhalation, and they can be used for the related risk assessment.